EAA Sport Aviation

Solar Impulse

more efficient, more reliable, no emissions– a portrait so alluring one speaker admitted, “It almost sounds like snake oil.” Burt Rutan, making an impassioned presentation, proclaimed, “I’ve dreamed about doing electric airplanes ever since I was a kid.” FAA Administrator Randy Babbitt, making the keynote address, put out his agency’s welcome mat for the technology: “We’re going to give it a big thumbs-up,” he said.

But the most enthusiastic response was reserved for Bertrand and his partner, Frenchman André Borschberg, developers of Solar Impulse HB-SIA. A solar-powered prototype aircraft with the wingspan of an Airbus A340 and the heft of a mid-size car, it was designed to fulfill the promise Bertrand had made the day he landed Breitling Orbiter 3: to circumnavigate the Earth without fossil fuel. On July 7, 2010, André took off from the project’s home base at Payerne airfield, Switzerland, and flew Solar Impulse through a complete diurnal solar cycle— more than 24 hours—its engines drawing direct solar power during the day and being powered through nine hours of darkness by sun-charged batteries.

“If a manned aircraft can stay aloft through the night on stored solar power,” Bertrand told attendees triumphantly, “theoretically it can stay aloft forever.”

PIONEERING HERITAGE

By many measures Solar Impulse could claim title as the world’s ultimate homebuilt—if you expand your definition of home to include a state-of-the-art development center in Lausanne, Switzerland, along with the hangar complex at Payerne. With a 208.1-foot wingspan, Solar Impulse is 100 feet longer from wingtip to wingtip than Voyager. Coupled with its 3,520- pound ( 1,600-kilogram) gross weight, it must also have the most lightly loaded wing—about 2 pounds per square foot—of any manned aircraft. (A high-tech glider

After flying all day and through the night, on July 7, 2010, André was excited to see the sun rise and watch the battery level charge increase as energy began to circulate through the solar panels again.